Memory cells, arrays of memory cells, and methods of forming the same with sealing material on sidewalls thereof are disclosed herein. One example of forming a memory cell includes forming a stack of materials, forming a trench to a first depth in the stack of materials such that a portion of at least one of the active storage element material and the active select device material is exposed on sidewalls of the trench. A sealing material is formed on the exposed portion of the at least one of the active storage element material and the active select device material and the trench is deepened such that a portion of the other of the at least one of the active storage element material and the active select device material is exposed on the sidewalls of the trench.